diff options
Diffstat (limited to 'arch/sh/mm/fault_64.c')
| -rw-r--r-- | arch/sh/mm/fault_64.c | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/arch/sh/mm/fault_64.c b/arch/sh/mm/fault_64.c new file mode 100644 index 0000000..1469aa7 --- /dev/null +++ b/arch/sh/mm/fault_64.c @@ -0,0 +1,279 @@ +/* + * The SH64 TLB miss. + * + * Original code from fault.c + * Copyright (C) 2000, 2001 Paolo Alberelli + * + * Fast PTE->TLB refill path + * Copyright (C) 2003 Richard.Curnow@superh.com + * + * IMPORTANT NOTES : + * The do_fast_page_fault function is called from a context in entry.S + * where very few registers have been saved. In particular, the code in + * this file must be compiled not to use ANY caller-save registers that + * are not part of the restricted save set. Also, it means that code in + * this file must not make calls to functions elsewhere in the kernel, or + * else the excepting context will see corruption in its caller-save + * registers. Plus, the entry.S save area is non-reentrant, so this code + * has to run with SR.BL==1, i.e. no interrupts taken inside it and panic + * on any exception. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ +#include <linux/signal.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/ptrace.h> +#include <linux/mman.h> +#include <linux/mm.h> +#include <linux/smp.h> +#include <linux/interrupt.h> +#include <asm/system.h> +#include <asm/tlb.h> +#include <asm/io.h> +#include <asm/uaccess.h> +#include <asm/pgalloc.h> +#include <asm/mmu_context.h> +#include <asm/cpu/registers.h> + +/* Callable from fault.c, so not static */ +inline void __do_tlb_refill(unsigned long address, + unsigned long long is_text_not_data, pte_t *pte) +{ + unsigned long long ptel; + unsigned long long pteh=0; + struct tlb_info *tlbp; + unsigned long long next; + + /* Get PTEL first */ + ptel = pte_val(*pte); + + /* + * Set PTEH register + */ + pteh = address & MMU_VPN_MASK; + + /* Sign extend based on neff. */ +#if (NEFF == 32) + /* Faster sign extension */ + pteh = (unsigned long long)(signed long long)(signed long)pteh; +#else + /* General case */ + pteh = (pteh & NEFF_SIGN) ? (pteh | NEFF_MASK) : pteh; +#endif + + /* Set the ASID. */ + pteh |= get_asid() << PTEH_ASID_SHIFT; + pteh |= PTEH_VALID; + + /* Set PTEL register, set_pte has performed the sign extension */ + ptel &= _PAGE_FLAGS_HARDWARE_MASK; /* drop software flags */ + + tlbp = is_text_not_data ? &(cpu_data->itlb) : &(cpu_data->dtlb); + next = tlbp->next; + __flush_tlb_slot(next); + asm volatile ("putcfg %0,1,%2\n\n\t" + "putcfg %0,0,%1\n" + : : "r" (next), "r" (pteh), "r" (ptel) ); + + next += TLB_STEP; + if (next > tlbp->last) next = tlbp->first; + tlbp->next = next; + +} + +static int handle_vmalloc_fault(struct mm_struct *mm, + unsigned long protection_flags, + unsigned long long textaccess, + unsigned long address) +{ + pgd_t *dir; + pud_t *pud; + pmd_t *pmd; + static pte_t *pte; + pte_t entry; + + dir = pgd_offset_k(address); + + pud = pud_offset(dir, address); + if (pud_none_or_clear_bad(pud)) + return 0; + + pmd = pmd_offset(pud, address); + if (pmd_none_or_clear_bad(pmd)) + return 0; + + pte = pte_offset_kernel(pmd, address); + entry = *pte; + + if (pte_none(entry) || !pte_present(entry)) + return 0; + if ((pte_val(entry) & protection_flags) != protection_flags) + return 0; + + __do_tlb_refill(address, textaccess, pte); + + return 1; +} + +static int handle_tlbmiss(struct mm_struct *mm, + unsigned long long protection_flags, + unsigned long long textaccess, + unsigned long address) +{ + pgd_t *dir; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + pte_t entry; + + /* NB. The PGD currently only contains a single entry - there is no + page table tree stored for the top half of the address space since + virtual pages in that region should never be mapped in user mode. + (In kernel mode, the only things in that region are the 512Mb super + page (locked in), and vmalloc (modules) + I/O device pages (handled + by handle_vmalloc_fault), so no PGD for the upper half is required + by kernel mode either). + + See how mm->pgd is allocated and initialised in pgd_alloc to see why + the next test is necessary. - RPC */ + if (address >= (unsigned long) TASK_SIZE) + /* upper half - never has page table entries. */ + return 0; + + dir = pgd_offset(mm, address); + if (pgd_none(*dir) || !pgd_present(*dir)) + return 0; + if (!pgd_present(*dir)) + return 0; + + pud = pud_offset(dir, address); + if (pud_none(*pud) || !pud_present(*pud)) + return 0; + + pmd = pmd_offset(pud, address); + if (pmd_none(*pmd) || !pmd_present(*pmd)) + return 0; + + pte = pte_offset_kernel(pmd, address); + entry = *pte; + + if (pte_none(entry) || !pte_present(entry)) + return 0; + + /* + * If the page doesn't have sufficient protection bits set to + * service the kind of fault being handled, there's not much + * point doing the TLB refill. Punt the fault to the general + * handler. + */ + if ((pte_val(entry) & protection_flags) != protection_flags) + return 0; + + __do_tlb_refill(address, textaccess, pte); + + return 1; +} + +/* + * Put all this information into one structure so that everything is just + * arithmetic relative to a single base address. This reduces the number + * of movi/shori pairs needed just to load addresses of static data. + */ +struct expevt_lookup { + unsigned short protection_flags[8]; + unsigned char is_text_access[8]; + unsigned char is_write_access[8]; +}; + +#define PRU (1<<9) +#define PRW (1<<8) +#define PRX (1<<7) +#define PRR (1<<6) + +#define DIRTY (_PAGE_DIRTY | _PAGE_ACCESSED) +#define YOUNG (_PAGE_ACCESSED) + +/* Sized as 8 rather than 4 to allow checking the PTE's PRU bit against whether + the fault happened in user mode or privileged mode. */ +static struct expevt_lookup expevt_lookup_table = { + .protection_flags = {PRX, PRX, 0, 0, PRR, PRR, PRW, PRW}, + .is_text_access = {1, 1, 0, 0, 0, 0, 0, 0} +}; + +/* + This routine handles page faults that can be serviced just by refilling a + TLB entry from an existing page table entry. (This case represents a very + large majority of page faults.) Return 1 if the fault was successfully + handled. Return 0 if the fault could not be handled. (This leads into the + general fault handling in fault.c which deals with mapping file-backed + pages, stack growth, segmentation faults, swapping etc etc) + */ +asmlinkage int do_fast_page_fault(unsigned long long ssr_md, + unsigned long long expevt, + unsigned long address) +{ + struct task_struct *tsk; + struct mm_struct *mm; + unsigned long long textaccess; + unsigned long long protection_flags; + unsigned long long index; + unsigned long long expevt4; + + /* The next few lines implement a way of hashing EXPEVT into a + * small array index which can be used to lookup parameters + * specific to the type of TLBMISS being handled. + * + * Note: + * ITLBMISS has EXPEVT==0xa40 + * RTLBMISS has EXPEVT==0x040 + * WTLBMISS has EXPEVT==0x060 + */ + expevt4 = (expevt >> 4); + /* TODO : xor ssr_md into this expression too. Then we can check + * that PRU is set when it needs to be. */ + index = expevt4 ^ (expevt4 >> 5); + index &= 7; + protection_flags = expevt_lookup_table.protection_flags[index]; + textaccess = expevt_lookup_table.is_text_access[index]; + +#ifdef CONFIG_SH64_PROC_TLB + ++calls_to_do_fast_page_fault; +#endif + + /* SIM + * Note this is now called with interrupts still disabled + * This is to cope with being called for a missing IO port + * address with interrupts disabled. This should be fixed as + * soon as we have a better 'fast path' miss handler. + * + * Plus take care how you try and debug this stuff. + * For example, writing debug data to a port which you + * have just faulted on is not going to work. + */ + + tsk = current; + mm = tsk->mm; + + if ((address >= VMALLOC_START && address < VMALLOC_END) || + (address >= IOBASE_VADDR && address < IOBASE_END)) { + if (ssr_md) + /* + * Process-contexts can never have this address + * range mapped + */ + if (handle_vmalloc_fault(mm, protection_flags, + textaccess, address)) + return 1; + } else if (!in_interrupt() && mm) { + if (handle_tlbmiss(mm, protection_flags, textaccess, address)) + return 1; + } + + return 0; +} |